It is well known in motor vehicles to provide an air bag module mounted to a vehicle steering wheel including a hub portion. A typical driver's side air bag module includes an air bag having a circular bag opening and a generally circular inflator positioned partially within the bag opening of the air bag for discharging inflator gas thereinto upon sensing certain predetermined vehicle conditions. Also in the module, the inflator and air bag are housed within a housing and covered by a cover. The module further includes a retainer plate having a circular plate opening. The air bag, inflator, housing and cover are mounted to the retainer plate to form the module. The retainer plate also includes mounting members for mounting the assembled air bag module to the hub portion of the steering wheel.
During assembly of the air bag module, it is desirable to have the air bag mounted to the retainer plate as a separate subassembly such that the retainer plate may then be used to position and support the air bag during the operation of folding the air bag. The mechanism for attaching the air bag to the retainer plate must also anchor the air bag to the retainer plate during air bag inflation. In the prior art, attachment of the air bag to the retainer plate has typically been accomplished by using a multiplicity of fasteners to fasten the air bag to a multiplicity of apertures in the retainer plate. This operation is time-consuming during assembly of the module.
An alternate mechanism has been suggested in the prior art for attaching the air bag to the module without the use of fasteners. This arrangement involves providing a beaded perimeter on the air bag which is preassembled with the inflator by securing the beaded perimeter to an annular groove on the inflator after which the inflator is inserted into and coupled with a cup-shaped retainer which traps the beaded perimeter between the inflator and cup-shaped retainer. However, this air bag attachment method has the disadvantages of requiring a complex cup-shaped retainer, of not being adaptable to existing air bag modules utilizing a retainer plate with a circular opening, and of not having a separate air bag subassembly including the retainer plate which facilitates the air bag folding operation.